Riding Mower Motor Control for Heavy-Load Rotor Position Detection
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Solution Overview
Problem
Existing mower technologies face challenges in accurately determining the rotor position of electric motors during heavy-load operations, leading to potential motor stoppages and user experience issues due to contradictions in rotational speed estimation.
Innovation Solution
A manned mower system that includes a controller to manage bus current and selectively use high-frequency signal injection or flux observer methods to determine rotor position, ensuring the motor operates within a controlled current range and speed thresholds to prevent stoppages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the existing detection method without position sensor is used to detect rotor position by measuring back electromotive force and deducing rotational speed, then the device complexity is reduced, but the measurement precision of rotor position deteriorates during heavy-load operation causing motor stoppages
Solution Approach 1:
The patent applies dynamics by making the rotor position detection method adjustable based on operating conditions. The controller dynamically switches between different detection methods (with or without position sensor) depending on whether the motor is operating under light or heavy load, thereby optimizing both device complexity and measurement precision across different operational states
Solution Approach 2:
The patent changes the detection parameter strategy based on load conditions. During heavy-load operation, it switches to position sensor-based detection to maintain measurement precision, while during light-load operation, it uses back electromotive force measurement to reduce device complexity. This parameter change approach resolves the contradiction between complexity and precision
2Device complexity
If the existing detection method without position sensor is used during heavy-load operation, then the device complexity is reduced, but the reliability of motor operation deteriorates due to inaccurate rotor position acquisition causing motor stoppages
Solution Approach 1:
The system dynamically adjusts the detection method based on real-time operating conditions. When heavy load is detected, it switches to the more reliable position sensor-based detection method, ensuring motor operation reliability while maintaining reasonable device complexity through conditional rather than constant use of sensors
3Measurement precision
If the bus current is limited within a preset range during heavy-load operation, then the rotor position determination accuracy is improved, but the power output of the motor is reduced
Solution Approach 1:
The current limitation is applied dynamically only during heavy-load rotor position detection to improve determination accuracy, while allowing full power output during normal operation. This temporal and conditional application resolves the contradiction between accuracy and power by restricting current limitation to specific detection phases rather than continuous operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively maintains motor operation under heavy loads by accurately determining rotor position, preventing stoppages and enhancing user experience.
Implementation Method 1
the back electromotive force is measured by injecting high-frequency signals
Implementation Method 2
the second method includes a flux observer
Data Source
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AI summary
A manned mower includes a vehicle frame and a support portion used for supporting a user; a traveling wheel set supporting the vehicle frame; a mowing element driven by a mowing electric motor; and a controller configured to apply a drive signal to a driver circuit to control the operation of the mowing electric motor. The controller is configured to receive a first electrical parameter related to the current of the mowing electric motor and when the first electrical parameter satisfies a first preset condition, limit the first electrical parameter within a preset range. When the first electrical' parameter is limited within the preset range, the controller is further configured to selectively use a first method or a second method to determine the rotor position of the mowing electric motor so that the mowing electric motor does not stop when the first electrical parameter is within the preset range.